The School Amplifier

Øistein Klevhus, now at FHI (the Norwegian Institute of Public Health), and myself did a project together at the end of our engineering school. I am greatly in debt to Øistein, because he was the one who made it possible for me to go through with that school — I was far too busy with EC, and had far too little time for school. Øistein came over to me at EC with schoolwork tasks and other stuff I had to do, and in that way it was possible for me to get through the school without nearly being present. I am forever grateful for that!

The amplifier: it was a very special design, fully complementary, and used matched single field-effect transistors at the input, along with some very interesting output transistors that had a very low turnover point.

More info on the matching of the input transistors will follow, but for now: they required manual matching, and it wasn’t easy to find a pair that worked. Note also the very low emitter resistors on the output stage — this matches a later paper I did for the AES; see the AB distortion paper.